The present invention relates to a ground lining, a covering for creating a green area or a sports field as well as a method for laying a green area.
Ground linings for regulating the water balance of an area of ground, for example, of a sports field are disclosed in German Patent Application DE 197 20 006 A1. Described there are grid panels which are interconnectable to form a lining and which have elevations and depressions at their upper sides for storing a residual moisture. These ground linings have proven to be efficient for covering structures having a normal moisture requirement. For covering structures having an increased moisture requirement or green areas which are subject to a long dry period, increased demands are made on the regulating capability of the water balance in the ground.
A further ground lining as well as a covering for creating a riding field is described in German Patent Application DE 44 16 943 A1. The upwardly open design of the ground panels with the upwardly projecting edges of the individual hexagonal panel elements are, on one hand, sensitive to damage, in particular, when the ground panels are laid bare as part of a riding field covering. This will then also involve a risk of injury to the persons or animals stepping on the covering. Moreover, the water regulating capability of such an open structure is reduced.
The same applies to the grid panels which disclosed in the publications U.S. Pat. No. 5,816,738; DE 297 07 770 U1; DE 196 32 070 C2; EP 0 516 957 A1 und DE 44 15 595 A1 and which are partly usable for grass areas.
Also, with respect to the ability of ground linings to be laid over large surfaces, it is useful for these ground linings to be able to be quickly laid down onto the subgrade or the surface of the ground; here, increased demands are to be made on the connecting elements between the panels in terms of flexibility and strength.
In the case of ground elements having variations in temperature, it must be possible to compensate for expansions between the panels. The intention for the present invention is, moreover, to contribute to accelerate the laying of green areas even in difficult ground and climate conditions by means of a suitable method.
The present invention provides a ground lining for regulating the water balance of an area of ground comprising a combination of ground panels (5) which can be placed against each other and which feature a panel covering (51) having a plurality of cover openings (16a, b) to allow the passage of water, wherein the ground lining (6) features a panel base (52) which is located at a distance from the panel covering (51), several reservoirs (54) being provided between the panel base (52) and the panel covering (51) and separated from each other by dividing walls (53) that extend between the panel base (52) and the panel covering (51); and adjacent reservoirs (54) are interconnected by an overflow (55).
The present invention also provides a ground lining comprising a combination of square ground panels (5) which can be placed against each other and which are bordered by surrounding side walls (56), wherein two side walls (56) meeting at a corner each have an integrally molded hook (8) for connecting adjacent ground panels (5) and the remaining two side walls (56) feature pockets (81) for the engagement of the hooks (8).
A covering of a sports field or of a green area is also provided, the covering comprising a subgrade (1) and an overlaying surface structure (2) featuring at least one walked-on layer (7), wherein a ground lining (6) is arranged between the walked-on layer (7) and the subgrade (1). A method for laying a green area is provided, comprising the following method steps: construction of the covering; the ground lining (6), which is filled with a substrate which promotes the growth of grass or with liquid, being laid prior to placing the walked-on layer (7); applying the walked-on layer (7), sprinkling grass seeds over the walked-on layer (7), and watering the walked-on layer (7).
The regulation of the water balance within the structure of the covering is essential for the lasting preservation of green areas such a grass area, sports fields, etc. To minimize the cost intensive artificial irrigation outlay, especially during dry periods or in climatically unfavorable regions of the earth, the present invention makes provision for reservoirs for storing water to be integrated in the ground panel. While in the related art, provision is made for the moisture to be stored only above the panel plane, in direct contact with the overlaying surface structure or the layer that is walked on, the reservoirs that extend underneath the panel base ensure a longer-lasting storage capacity and therefore a longer moisture supply phase to the structure above. It is important for this that the reservoirs be configured inside the ground panel in a closed manner, that is without direct contact to the overlaying covering structure. The overflows between the reservoirs ensure that a locally increased accumulation of water can be distributed over the adjacent reservoirs so that a homogeneous water regulating capability is provided in the cover or ground lining. By an additional profiling of the panel covering, for example with elevations and depressions, it is possible, on one hand, to influence the regulating capability additionally and, on the other hand, to increase the stiffness of the ground lining, which is advantageous in the case of compressive loading of the lining. The adhesion and interconnection with the adjacent layer is increased as well.
It is to be regarded as a further advantage that, using the surface contour of the ground panels constituted by the elevations and depressions, it was possible to find a surface contour which counteracts the flow behavior of the walked-on layer and which not only prevents the walked-on layer from being laterally displaced between the elevations within the walked-on layer but which also suppresses a lateral displacement above the elevations in an effective manner. This effect is based on that fact that a local compressive load gives rise to a conical pressure distribution in the walked-on layer which is largely compensated for due to the surface of the ground panels which is structured by elevations. This compensation effect is intensified by the wall of the elevations which is slanted in design and generally has a conical or pyramidal shape so that, in response to the pressure, for example of a horse""s hoof, an oppositely directed pressure distribution develops in the walked-on layer. This pressure distribution counteracts the conical pressure shape resulting from the horse""s hoof. Thus, the horizontal pressure component underneath the horse""s hoof is largely neutralized and a lateral spreading of the walked-on layer (sand) above the elevations is effectively prevented. In a further embodiment of the present invention, the elevations are staggered by rows so as to hinder the walked-on layer from flowing along the troughs. Such an arrangement ensues also in a chessboard-like arrangement of the elevations when, in lieu of a trough crossing, an elevation is located between four adjacent elevations. These second elevations can then have a different design than the aforementioned first elevations. The second elevations could be designed, for example, without depression or smaller.
Should the ground panels nevertheless be locally cleared of the walked-on layer, then the surface structure turns out to be largely insensitive to impact effects since the elevations are always designed to have a larger surface than a web-like partitioning of the surface. Therefore, damage to the ground panels by an external influence and a resulting risk of injury are not to be expected.
A further advantage of the ground lining consists in the flexible design of the ground panels which ensues from the waved structure of the successive elevations and troughs. Advantageous is also the flexibility of the panel perpendicularly to the panel plane. A loading of the ground panel gives rise to a local plunging of the elevations into unfilled hollow spaces underneath the ground panel, enabling the flexibility. The elasticity of the ground lining resulting from this ensures unvarying ground conditions over a large surface.
The design of the ground lining according to the present invention makes it suitable for coverings of any kind so that the ground lining is also suitable for driveways and walkways as well as for storage areas in warehouses where it is directly contacted.
By forming hooks on the edges of the ground panels on both sides of a corner, it is possible to form a large-surface interconnected ground lining which can also be wound onto and unwound from a mandrel so that a rapid laying of large-surface ground linings is possible. The U-shaped design of the hooks permits the flexibility required during the winding up and unwinding of the lining, i.e., of the panels.
Because of the capability of filling the reservoirs in the ground panels also with substrates which promote ground or green area growth, it is possible to accelerate the creation of a green area by laying ground panels which are filled in this manner.